Scientists reveal secret of an amazing phenomenon in the atmosphere of Mars

Every year in the spring, a huge cloud appears in the atmosphere of Mars, which would occupy an area of 2/3 of Ukraine. Its dimensions are so huge that it is clearly visible from the Mars Express orbiter. The most interesting thing is that all these years such a strange and huge atmospheric phenomenon has been elusive for a very long time. Now scientists know why.

The elongated Arsia Mons cloud, discovered on Mars in 2018, is considered the longest in the Solar System, which is formed from an extinct volcano higher than any on Earth. Authorship: ESA

Gigantic size

The cloud was first noticed in 2018 by astrophysicist Jorge Hernandez Bernal. Bernal and his team published their observations in 2020. Amazing in shape and size, the long cloud was named Arsia Mons, or AMEC for short. It is believed that it is the longest of its kind in the Solar System, because it has a length of 1770 km.

The huge Arsia Mons cloud returns year after year in the spring on Mars. Authorship: ESA

For two years, researchers tried to explain the reason for its appearance, because the cloud consistently appeared in the same place every Martian year. Recently, the Journal of Geophysical Research: Planets team shared the results of their work. As it turns out, the cloud creates an extinct volcano. The ancient mountain, once spewing lava, is about 430 km wide at the base and rises 17 km into the sky. Its size surpasses Mauna Loa – the largest volcano on Earth, which height is 4169 m.

Mars Express spacecraft. Image: ESA

How does a strange long cloud form?

When spring comes in the south of Mars, the air in the area of the volcano begins to warm up to 12 °C. The ice in the crater of the volcano begins to evaporate rapidly and condense in a dry atmosphere at an altitude of 45 km. This condensate is picked up by the wind, which inflates it at a speed of 20 m/s. Thus, an extended haze is formed, creating a thin tail over the top of the mountain, like smoke from a steam train. It stretches for almost 2 thousand km, and then disappears under the warm sunlight in a matter of hours.

The peculiarity of the giant cloud is how it has remained unnoticed for so long. This is due to the work of the MRO and Mars Express orbiters, which are configured to start work in the afternoon. The giant cloud appeared for only three hours in the morning on one day of the year, when the spacecraft were still “asleep”.

Earlier we reported on how NASA asked for help with the search for Martian clouds.

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